CORROSION AND CORROSION PROTECTION OF ENGINEERING ALLOYS
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- Versione italiana
- Academic year
- 2022/2023
- Teacher
- ANDREA BALBO
- Credits
- 6
- Didactic period
- Secondo Semestre
- SSD
- ING-IND/22
Training objectives
- In industrialized countries, the cost of corrosion is estimated at around 3 to 4% of gross domestic product and could be reduced by 15-20% through the proper choice of materials and the application of methods and protection techniques that apply basic knowledge already acquired in this field. The course thus provides skills and experience of laboratory practices, which will allow the student to understand the nature of corrosion phenomena on metallic materials, and will help to reduce potential failures/damages due to corrosion. These skills are highly qualifying for mechanical engineers who operate in different fields from the production to the design. This knowledge will assist in:
- Implementing the correct choice of materials in relation to the environment and the specific application
- Adopting design choices that can ensure the best corrosion resistance of the materials
- Directing towards preventive approaches suitable to avoid corrosion problems
- Identifying the causes of ongoing corrosion phenomena
- Proposing appropriate remedies to eliminate corrosion phenomena or at least reduce corrosion rates to acceptable levels
- Saving operational and maintenance costs. Prerequisites
- The study of corrosion and degradation of metallic materials is strongly multidisciplinary. Therefore, it requires basic integrated knowledge provided by the courses of Chemistry (the nature and properties of atomic bonds, the solid-state structure and elementary thermodynamics concepts), Metallurgy (microstructure of alloys, influence of heat treatments and mechanical processing), along with an elementary knowledge of Physics (concepts of electric potential, electric current and current density).
Course programme
- The course includes 40 hours of teaching and 20 h of laboratory practice. For each topic, the theoretical bases are presented and successively the notions are verified and supported by laboratory activity. The students are requested to investigate possible causes and solutions for a practical case of corrosion attack.
Definition of corrosion. Technical and economic significance of corrosion. Morphology of corrosion attacks (1h + 1h Lab)
Quantitative measure of corrosion rates over time. Electrochemical corrosion mechanisms. Thermodynamics of cathodic and anodic processes. Potential / pH diagrams (4h + 1h Lab)
Kinetics of corrosion reactions: mixed potential theory, passivity, effect of mass transfer, electrochemical methods to measure the corrosion rates (8 h + 2 h Lab)
Conditions of cathodic and anodic protection. Factors affecting the corrosion rates: time, temperature, chemical, biochemical and environmental factors, flow rate and influence of plant design (3 h + 1 h Lab)
Uniform corrosion, galvanic corrosion, crevice corrosion, pitting, filiform corrosion, intergranular corrosion, stress corrosion, corrosion fatigue, fretting corrosion. Damage by hydrogen penetration. Microbiological corrosion. Stray current corrosion (12 h + 5 h Lab)
Corrosion protection methods: inhibitors, surface treatment, cathodic and anodic protection. General information on cathodic protection. Monitoring of cathodic protection. Sacrificial anodes. Anodes impressed current systems. (8 h + 2 h Lab)
Corrosion in soils. Marine corrosion. Corrosion in concrete. (4 h + 2 h Lab)
Practical cases of corrosion attack or failure by corrosion. Laboratory activity and selected readings to prepare a report evidencing possible causes of corrosion and proposing useful solutions to mitigate the problem (6 h Lab). Didactic methods
- The course consists of lectures to explain fundamentals of corrosion science and technology with the help of a visual support (slideshow) and class discussion. The comprehension of the different topics is also sustained by a learning-by-doing method based on laboratory activity. Selected case studies are assigned to groups of students who are requested to present a final report discussing possible corrosion causes and mitigation solutions. The report preparation involves laboratory activity and recommended reading.
Learning assessment procedures
- The achievement of the learning goals is assessed by an oral examination and by the quality of the report related to the investigated case study. The final grade is formulated on account of:
- Competence achieved in the studied discipline (50%)
- Correct use of technical language and clarity of exposition (20%)
- Understanding of the case study investigated and choices suggested to mitigate corrosion (30%). Reference texts
- P. Pedeferri, Corrosione e Protezione dei Materiali Metallici (VOL.1 e 2), Edizioni Città Studi, Milano
G. Bianchi, F. Mazza, Corrosione e Protezione dei Metalli, AIM, Milano.
M.G. Fontana, Corrosion Engineering, McGraw Hill, N.Y.
